Backlight assembly and display apparatus having the same

ABSTRACT

A backlight assembly includes a light source generating light and a first optical member diffusing the light. The first optical member includes a first diffusion member provided on an exit surface of the first optical member, from which the light exits, to diffuse the light. The first diffusion member includes a plurality of edges each having a curved shape and extending between the exit surface and a vertex of the first diffusion member. Accordingly, the light exiting through the exit surface is effectively diffused by the edges of the first diffusion member.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patentapplication Ser. No. 12/698,040 filed on Feb. 1, 2010, which claimspriority to Korean Patent Application No. 10-2009-0064994 filed on Jul.16, 2009, in the Korean Intellectual Property Office (KIPO), and all thebenefits accruing therefrom under 35 U.S.C. §119, the contents of theprior applications being herein incorporated by reference.

BACKGROUND

1. Field of the Invention

The present invention relates to a backlight assembly and a displayapparatus having the same. More particularly, the present inventionrelates to a backlight assembly capable of providing substantiallyuniform light, and a display apparatus having the backlight assembly.

2. Description of the Related Art

In general, a display apparatus includes a backlight assembly thatgenerates light and a display panel that displays an image by using thelight from the backlight assembly. Accordingly, a backlight assemblycapable of uniformly providing light to the entire display panelimproves the display quality of the display apparatus.

Recently, light emitting diodes have become widely used as the lightsource in the backlight assembly of display apparatuses, instead of coldcathode fluorescent lamps. The cold cathode fluorescent lamp serves as aline light source, and, in contrast, the light emitting diode serves asa point light source. Because conventional optical sheets, such asdiffuser panels, were developed based on the optical properties of theline light source provided by cold cathode fluorescent lamps, theluminance of the light supplied to a display panel from a backlightassembly that employs the point light source provided by light emittingdiodes can become irregular when the conventional optical sheet, such asa diffuser panel, is used.

SUMMARY

In one aspect the invention provides a backlight assembly capable ofproviding substantially uniform light.

Another aspect of the invention also provides a display apparatus havingthe backlight assembly.

According to another aspect, a backlight assembly includes a lightsource that generates a light and a first optical member. The firstoptical member includes an incident surface to which the light isincident, an exit surface facing the incident surface, from which thelight exits, and a first diffusion member disposed on the exit surfaceto diffuse the light. The first diffusion member includes a plurality ofinclined surfaces that meet at a vertex, and the edges of the inclinedsurfaces extend between the exit surface and the vertex spaced apartform the exit surface and have curved shape.

According to another aspect, a display apparatus includes a backlightassembly that includes a light source that generates a light and a firstoptical member that diffuses the light, and a display panel receivingthe light from the backlight assembly to display an image.

The first optical member includes an incident surface to which the lightis incident, an exit surface facing the incident surface, from which thelight exits, and a first diffusion member disposed on the exit surfaceto diffuse the light.

The first diffusion member includes a plurality of inclined surfacesthat meet at a vertex and a plurality of edges of the inclined surfaces.The edges of the inclined surfaces extend between the exit surface andthe vertex spaced apart from the exit surface and have a curved shape.

The optical member may diffuse the light from the backlight assembly byusing the diffusion members provided on the incident and exit surfacesthereof in various shapes. In addition, when the backlight assemblyincludes a plurality of point light sources, the optical member mayeffectively diffuse the light emitted from the point light sources.Thus, the distance between the optical member and the light sources inthe backlight assembly may be reduced, thereby reducing a volume of thebacklight assembly.

In addition, the backlight assembly provides the light to the entiredisplay apparatus uniformly, to thereby improve the image displayquality of the display apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other advantages of the present invention will becomereadily apparent by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings wherein:

FIG. 1 is an exploded perspective view showing a display apparatusaccording to an exemplary embodiment;

FIG. 2 is a sectional view taken along a line I-I′ of FIG. 1;

FIG. 3 is a perspective view showing a first diffusion member of FIG. 2;

FIG. 4 is a sectional view taken along a line II-II′ of FIG. 3;

FIG. 5 is a sectional view taken along a line III-III′ of FIG. 3;

FIG. 6 is a partially enlarged view showing a first optical member ofFIG. 2;

FIG. 7A is a partially enlarged plan view showing a reflection plateprovided with light sources;

FIG. 7B is a partially enlarged plan view showing a first opticalmember;

FIG. 8 is a view illustrating a method of fabricating a first opticalmember of FIG. 2; and

FIG. 9 is a graph showing luminance of a display apparatus of FIG. 1.

DESCRIPTION OF THE EMBODIMENTS

It will be understood that when an element or layer is referred to asbeing “on,” “connected to” or “coupled to” another element or layer, itcan be directly on, connected or coupled to another element or layer orintervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on,” “directly connected to”or “directly coupled to” another element or layer, there are nointervening elements or layers present. Like numbers refer to likeelements throughout. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, components, regions, layersand/or sections, these elements, components, regions, layers and/orsections should not be limited by these terms. These terms are only usedto distinguish one element, component, region, layer or section fromanother region, layer or section. Thus, a first element, component,region, layer or section discussed below could be termed a secondelement, component, region, layer or section without departing from theteachings herein.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below, depending on the orientation. The devicemay be otherwise oriented (rotated 90 degrees or at other orientations)and the spatially relative descriptors used herein interpretedaccordingly.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms, “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “includes”and/or “including,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Hereinafter, the present invention will be explained in detail withreference to the accompanying drawings.

FIG. 1 is an exploded perspective view showing a display apparatusaccording to an exemplary embodiment, and FIG. 2 is a sectional viewtaken along a line I-I′ of FIG. 1.

Referring to FIGS. 1 and 2, a display apparatus 500 includes a backlightassembly 200 that generates light, and a display panel 400 that receivesthe light from the backlight assembly 200 to display an image. Thedisplay apparatus 500 also includes a top chassis 380 and a bottomchassis 350 that is coupled with the top chassis 380 to receive thebacklight assembly 200 and the display panel 400 therein.

The backlight assembly 200 includes a reflection plate 20, a pluralityof light sources 50 arranged on the reflection plate 20, a first opticalmember 100, and a second optical member 180.

Each of the light sources 50 has an approximately point-shaped lightsource. The light sources 50 are arranged in a first direction D1 and asecond direction D2 that is substantially perpendicular to the firstdirection D1, and are spaced apart from each other. In the presentexemplary embodiment, the light sources 50 are spaced apart from eachother by a distance of about 25 millimeters in the first direction D1and by a distance of about 28 millimeters in the second direction D2.

In addition, in the present exemplary embodiment, each of the lightsources 50 may be a light emitting diode, but it should not be limitedthereto or thereby. Each of the light sources 50 may be replaced withanother point light source such as an organic light emitting diode.

The reflection plate 20 includes a material that reflects light, suchas, for example, polyethylene terephthalate, aluminum, etc., and isdisposed on a bottom of the bottom chassis 350. The reflection plate 20reflects the light provided from the light sources 50 to enhance theamount of the light used in the display panel 400 to display the image.

The first optical member 100 is disposed above the light sources 50 todiffuse the light emitted from the light sources 50. The first opticalmember 100 includes a body 170, first diffusion members 150 provided onan exit surface 100B of the body 170, and second diffusion members 175provided on an incident surface 100A of the body. The incident surface100A may be defined as a surface to which the light emitted from thelight sources 50 is incident, and the exit surface 100B may be definedas a surface from which the light incident to the body 170 exits. In thepresent exemplary embodiment, the first diffusion members 150 each havethe same structure, thus one of the first diffusion members 150 will bedescribed as a representative example of those members, and the samereference numerals are assigned to those components. In addition, in thepresent exemplary embodiment, the second diffusion members 175 all havethe same structure, thus one of the second diffusion members 175 will bedescribed as a representative example of those members, and the samereference numerals are assigned to those components.

Each of the first diffusion members 150 has a polyhedron shape of whicha bottom surface makes contact with the exit surface 100B and inclinedsurfaces are connected with the bottom surface. The inclined surfacesare connected with one vertex spaced apart from the bottom surface, andthe edges where two adjacent inclined surfaces meet each other have acurved shape. The first diffusion member 150 diffuses the light exitingto the exterior after sequentially passing through the body 170 and theexit surface 100B. The first diffusion member 150 will be described inmore detail below with reference to FIGS. 3 to 5.

The second diffusion members 175 are provided on the incident surface100A. Each of the second diffusion members 175 has an embossed shapethat protrudes from the incident surface 100A. Accordingly, the lightemitted from the light sources 50 and passing through the incidentsurface 100A may be diffused by a curved surface of the second diffusionmember 175.

The number of the second diffusion members 175, and the spacing betweensecond diffusion members 175, provided on the incident surface 100Adepends on the positions of the light sources 50. For example, in FIG.2, the area corresponding to the positions of the light sources 50 isdefined as a first area A1, and an area corresponding to the areabetween two light sources adjacent to each other is defined as a secondarea A2. The number of the second diffusion members 175 positioned inthe second area A2 increases as the second diffusion members 175 arespaced apart from a center of the second area A2. In other words, thesecond diffusion members 175 are spaced farther apart in the second areathan in the first area, and the space between each second diffusionmember is greatest in the center of the second area and decrease towardthe first area.

In general, increasing the distance between light sources and opticalmembers that diffuse the light emitted from the light sources increasesthe amount of the light that travels in different directions, and thusthe light diffusion effect created by the optical members is increased,which improves display quality. Increasing the distance between thelight sources and optical members that diffuse light emitted from thelight sources may, however, also increase the thickness of the backlightassembly. However, in the above-described display apparatus 500, becausethe first optical member 100 increases the diffusion effect of thelight, a distance between the first optical member 100 and each lightsource 50 may be equal to or smaller than 10 millimeters, and thus athickness of the display apparatus 500 may be equal to or smaller than20 millimeters.

The second optical member 180 is disposed on the first optical member100. The second optical member 180 may include a plurality of opticalfilms. For instance, the second optical member 180 may include areflective polarizer 181 that reflects or transmits the light from thefirst optical member 100 according to the vibration direction of thelight, a prism sheet 182 that condenses the light from the reflectivepolarizer 181 to improve the front brightness of the light, and adiffusion film 183 that diffuses the light from the prism sheet 182.

According to another exemplary embodiment, the second optical member 180may further include additional optical films having different functionsfrom the above-described optical films, or the same functions as theabove-described optical films.

In the present exemplary embodiment, the display panel 400 may be apanel for a liquid crystal display. In a case in which the display panel400 is the panel for the liquid crystal display, the display panel 400includes a first substrate 420 employing thin film transistors (notshown) and a second substrate 410 facing the first substrate 420. Thefirst substrate 420 includes a plurality of pixels (not shown) eachhaving a corresponding thin film transistor of the thin film transistorsand a pixel electrode (not shown) electrically connected to thecorresponding thin film transistor.

The second substrate 410 includes color filters (not shown) positionedin one-to-one correspondence with the pixels. In addition, if thedisplay panel 400 is the panel for the liquid crystal display, thesecond substrate 410 may include a common electrode (not shown) thatforms an electric field with the pixel electrode.

According to another exemplary embodiment, the color filters may beformed on the first substrate 420 instead of the second substrate 410,and also the common electrode may be formed on the first substrate 420,not on the second substrate 410. In the case in which the commonelectrode is formed on the first substrate 420, the common electrodeforms a horizontal electric field in cooperation with the pixelelectrode and serves as an opposite electrode to control directors ofliquid crystals.

The bottom chassis 350 includes a bottom and inclined surfaces thatextend from the bottom to provide a receiving space. The reflectionplate 20, the light sources 50, the first optical member 100, and thesecond optical member 180 are received in the receiving space. Inaddition, the display panel 400 is disposed on the second optical member180, and the top chassis 380 is coupled with the bottom chassis 350 tocover the end of the display panel 400.

FIG. 3 is a perspective view showing a first diffusion member 150 ofFIG. 2. In FIG. 3, only one first diffusion member 150 has been shown asa representative example since the first diffusion members 150 have thesame structure.

Referring to FIG. 3, the first diffusion member 150 includes a bottomsurface 115 making contact with the exit surface 100B and first, second,third and fourth inclined surfaces 111, 112, 113, and 114, respectively,extending from the bottom surface 115 and connected at the vertex 120.

The first inclined surface 111 includes a first edge 101 and a secondedge 102. The second inclined surface 112 includes a third edge 103 andco-owns the second edge 102 with the first inclined surface 111. Thethird inclined surface 113 includes a fourth edge 104 and co-owns thethird edge 103 with the second inclined surface 112. The fourth inclinedsurface 114 co-owns the first edge 101 with the first inclined surface111, and the fourth inclined surface 114 co-owns the fourth edge 104with the third inclined surface 113.

In the first diffusion member 150 having the above-described structure,the light provided to the first diffusion member 150 after passingthrough the bottom surface 115 is refracted by the first to fourthinclined surfaces 111, 112, 113, and 114 and the first to fourth edges101, 102, 103, and 104, thereby changing the path of the light.

In detail, when first, second, and third lights LT1, LT2, and LT3,respectively, traveling toward a third direction D3 are provided to thefirst diffusion member 150, the first to third lights LT1, LT2, and LT3are refracted by the fourth edge 104 after passing through the bottomsurface 115, and each travels toward a direction that is different fromthe third direction D3.

Each of the first to fourth edges 101, 102, 103, and 104 has a curvedshape. Thus, the lights refracted by the first to fourth edges 101, 102,103, and 104 after passing through the exit surface 100B may bedispersed in a variety of different directions. For instance, the firstto third lights LT1, LT2, and LT3 travel toward the third direction D3before being refracted by the fourth edge 104, but the first to thirdlights LT1, LT2, and LT3 each travel in different directions after beingrefracted by the fourth edge 104. That is, due to the curved shape ofthe fourth edge 104, the lights passing through the first diffusionmember 150 are dispersed in a variety of different directions, therebyincreasing the light diffusion effect.

Meanwhile, when a fourth light LT4traveling toward the third directionD3 reaches the first inclined surface 111 after passing through thebottom surface 115, the fourth light LT4is refracted by the firstinclined surface 111 to travel toward a direction different from thethird direction D3 since the first inclined surface 111 is inclinedtoward the vertex while extending from the bottom surface 115.

The light diffusion effect created by the first diffusion member 150 isshown in FIG. 9. FIG. 9 is a graph showing luminance of a displayapparatus of FIG. 1. In FIG. 9, the luminance (lux) has been obtained bymeasuring the light emitted from a display area having a size of 30mm×30 mm.

Referring to FIG. 9, an average value of the measured luminance isapproximately 1660 lux, a minimum value of the measured luminance isapproximately 1490 lux, and a maximum value of the measured luminance isapproximately 1840 lux. In other words, the display apparatus 500employing the first diffusion member 150 may display the image in aluminance difference of about 180 lux to about 350 lux.

Although not shown in FIG. 9, if the first optical member 100 does notinclude the first diffusion members 150 and the second diffusion members175, the minimum value of the luminance of the display apparatus may belowered below 1000 lux, so that the luminance difference may be variedover 700 lux. As the luminance difference of the image displayed on thedisplay apparatus increases, a bright/dark line occurs on the displayimage due to the luminance difference, thereby causing deterioration inimage display quality.

However, in the exemplary embodiments disclosed herein, the displayapparatus 500 employing the first optical member 100 may reduce theluminance difference of the displayed image, to thereby minimizedeterioration of the image display quality of the display apparatus.

FIG. 4 is a sectional view taken along a line II-II′ of FIG. 3.

Referring to FIG. 4, a cross-section of the first optical member 150,taken along the vertex 120, the first edge 101, and the third edge 103,has a first segment 140.

The first segment 140 is defined by the first edge 101, the third edge103 connected with the first edge 101 through the vertex 120, and afirst chord 130 connecting an end of the first edge 101 to an end of thethird edge 103.

In the present exemplary embodiment, the first chord 130 may have alength from about 30 micrometers to about 100 micrometers, and a firststraight distance H1 between the vertex 120 and the first chord 130 isfrom about 15 micrometers to about 50 micrometers.

In addition, a curve defined by the first and third edges 101 and 103connected with each other through the vertex 120 corresponds to aportion of an elliptical arc of a first ellipse 160 defined by a firstmajor axis L1 and a first minor axis S1 crossing the first major axis L1at a first center portion 125 of the first ellipse 160. That is, acurvature of the curve defined by the first and third edges 101 and 103may be defined by a curvature of the elliptical arc of the first ellipse160.

In the first ellipse 160 according to the present exemplary embodiment,a ratio of a length of the first minor axis S1 to a length of the firstmajor axis L1 is from 1:1 to 1:3. If the ratio of the length of thefirst minor axis S1 to the length of the first major axis L1 is 1:1, thefirst ellipse 160 may have a substantially circular shape.

In addition, an angle between a straight line connecting the end of thefirst edge 101 to the vertex 120 and the first chord 130 is referred toas a first angle θ1. The first angle θ1 is from about 20 degree to about40 degree.

FIG. 5 is a sectional view taken along a line III-III′ of FIG. 3.

Referring to FIG. 5, a cross-section of the first optical member 150,taken along the first edge 101 and the third edge 103, has a secondsegment 145.

The second segment 145 is defined by the second edge 102, the fourthedge 104 connected with the second edge 102 through the vertex 120, anda second chord 135 connecting an end of the second edge 102 to an end ofthe fourth edge 104.

In the present exemplary embodiment, the second chord 135 may have alength from about 30 micrometers to about 100 micrometers, and a secondstraight distance H2 between the vertex 120 and the second chord 135 isfrom about 15 micrometers to about 50 micrometers.

In addition, a curve defined by the second and fourth edges 102 and 104connected with each other through the vertex 120 corresponds to aportion of an elliptical arc of a second ellipse 165 defined by a secondmajor axis L2 and a second minor axis S2 crossing the second major axisL2 at a second center portion 126 of the second ellipse 165. That is, acurvature of the curve defined by the second and fourth edges 102 and104 may be defined by a curvature of the elliptical arc of the secondellipse 165.

In the second ellipse 165 according to the present exemplary embodiment,a ratio of a length of the second minor axis S2 to a length of thesecond major axis L2 is from 1:1 to 1:3. If the ratio of the length ofthe second minor axis S2 to the length of the second major axis L2 is1:1, the second ellipse 165 may have a substantially circular shape.

In addition, an angle between a straight line connecting the end of thesecond edge 102 to the vertex 120 and the second chord 135 is referredto as a second angle θ2. The second angle θ2 is from about 20 degree toabout 40 degree.

Referring again to FIG. 3, the cross-section of the first diffusionmember 150, which is taken along the line II-II′, is the same as thefirst segment 140, and the elliptical arc of the first segment 140 isthe same as the portion of the elliptical arc of the first ellipse 160.In addition, the cross-section of the first diffusion member 150, whichis taken along the line III-III′, is the same as the second segment 145,and the elliptical arc of the second segment 145 is the same as theportion of the elliptical arc of the second ellipse 160.

In the present exemplary embodiment, because the first segment 140 issubstantially same as the second segment 145, the first ellipse 160 issubstantially same as the second ellipse 165. However, it should not belimited thereto or thereby, and thus the first segment 140 may bedesigned to have a shape that is different from that of the secondsegment 145.

FIG. 6 is a partially enlarged view showing a first optical member ofFIG. 2.

Referring to FIG. 6, the second diffusion member 175 is provided on theincident surface 100A of the first optical member 100. The seconddiffusion member 175 has the embossed shape protruding from the incidentsurface 100A.

In the present exemplary embodiment, the second diffusion member 175 hasa surface making contact with the incident surface 100A, and the surfaceof the second diffusion member 175 has a width 179 of about 30micrometers to about 100 micrometers. In addition, the second diffusionmember 175 protruding from the incident surface 100A has a height 178 ofabout 10 micrometers to about 40 micrometers.

The light emitted from the light sources 50 and traveling toward thefirst optical member 100 is refracted at the surface of the seconddiffusion member 175, so that the direction the light travels is varied.For instance, a fifth light LT5 and a sixth light LT6, which are emittedfrom the light sources 50 to travel toward the third direction D3, arerefracted by the curved surface of the second diffusion member 175 totravel toward directions different from the third direction D3.

The light emitted from the light sources 50 that travels toward thethird direction D3 is vertically emitted from the light sources 50.Accordingly, the second diffusion member 175 disperses the travelingpath of the light substantially vertically emitted from the lightsources 50, and as a result, the light diffusion effect of the lightemitted from the light sources 50 is increased by the second diffusionmember 175.

Meanwhile, as shown in FIG. 6, a fine concavo-convex pattern 177 may beformed in a valley positioned between two second diffusion members thatare adjacent to each other. The fine concavo-convex pattern 177 scattersthe lights traveling toward the valley in a variety of directions,thereby preventing a moiré phenomenon caused by optical interference.

FIG. 7A is a partially enlarged plan view showing a reflection plateprovided with light sources, and FIG. 7B is a partially enlarged planview showing a first optical member.

Referring to FIGS. 7A and 7B, the light sources 50 are arranged on thereflection plate 20. The light sources 50 are arranged in the firstdirection D1 and the second direction D2, which is substantiallyperpendicular to the first direction D1, and are spaced apart from eachother. In particular, the light sources 50 are spaced apart from eachother by a first interval 51 in the first direction D1 and spaced apartfrom each other by a second interval 52 in the second direction D2.

As described with reference to FIG. 6, the second diffusion member 175protrudes from the incident surface 100A to have an embossed shape, andthe number of the second diffusion members 175 provided on the incidentsurface 100A depends on the positions of the light sources 50.

Hereinafter, the number of the second diffusion members 175 will bedescribed as a pattern density.

In the present exemplary embodiment, for example, the first interval 51and the second interval 52 may be approximately 25 millimeters and 28millimeters, respectively. When each of the first and second intervals51 and 52 are divided into seven equal parts, a rectangular area definedby the first and second intervals 51 and 52 is divided into forty-ninelattice areas 55. Thus, each lattice area 55 has a long side of about 4millimeters and a short side of about 3.57 millimeters.

When the pattern density is defined by the number of the seconddiffusion members 175 provided in each lattice area 55, the patterndensity becomes a maximum at the lattice areas that overlap the lightsources 50, and becomes a minimum at the lattice areas that overlap thearea between two light sources. For instance, assuming that the patterndensity at the lattice areas overlapped with the light sources 50 is 1,the pattern density at the lattice areas overlapped between two lightsources adjacent to each other is about 0.2. In addition, the patterndensity gradually increases from 0.2 to 1 from the center of the latticeareas that overlap the area between two light sources to the latticeareas that overlap with the light sources. In other words, the seconddiffusion members 175 are spaced farther apart in the lattice areas thatoverlap a center of the area between two light sources, and becomecloser together as the lattice areas become nearer to a center of thelattice areas that overlap with the light sources 50.

FIG. 8 is a view illustrating a method of fabricating a first opticalmember of FIG. 2.

Referring to FIG. 8, an extrusion molder 600 includes a first roller R1,a second roller R2, and a third roller R3, which are arranged verticallyone above another.

In order to manufacture the first optical member 100 using the extrusionmolder 600, a polymer resin 300A in a molten state is provided to thefirst roller R1. The polymer resin 300A includes a first surface 301 anda second surface 302 opposite to the first surface 301.

When the polymer resin 300A is provided to the first roller R1, thefirst and second rollers 301 and 302 are rotated in mutually oppositedirections to pressurize the polymer resin 300A, so that the firstdiffusion members 150 (shown in FIG. 2) are formed on the first surface301 by a pattern (not shown) formed on a surface of the first roller R1.As a result, a first preliminary plate 300B is formed, having the firstdiffusion members formed on the first surface 301. The pattern formed onthe surface of the first roller R1 may have a recessed shape tooppositely correspond to the shape of the first diffusion members.

Then, the second diffusion members 175 (shown in FIG. 2) are formed onthe second surface 302 of the polymer resin 300A by a pattern (notshown) formed on a surface of the second roller R2. As a result, asecond preliminary plate 300C is formed, having the second diffusionmembers formed on the second surface 302. The pattern formed on thesurface of the second roller R2 may have a recessed shape to oppositelycorrespond to the shape of the second diffusion member.

Next, the second and third rollers R2 and R3 are rotated in mutuallyopposite direction to pressurize the second preliminary plate 300C.Thus, the fine concavo-convex pattern 177 (shown in FIG. 6) is formed onthe second surface 302 by a plurality of beads (not shown) formed on asurface of the third roller R3. As a result, a third preliminary plate300D is formed, having the fine concavo-convex pattern formed after thesecond diffusion members are formed.

Then, the third preliminary plate 300D is cured and is cut into thedesired size, thereby completely manufacturing the first optical member100.

Although exemplary embodiments have been described, it is understoodthat the present invention should not be limited to these exemplaryembodiments but various changes and modifications can be made by oneordinary skilled in the art within the spirit and scope of the presentinvention as hereinafter claimed.

What is claimed is:
 1. A backlight assembly comprising: a light sourcethat generates light; and a first optical member, wherein the firstoptical member comprises: a body including an incident surface to whichthe light is incident and an exit surface facing the incident surface,from which the light exits; and a first diffusion member disposed on theexit surface to diffuse the light, wherein the first diffusion membercomprises: a single vertex; four inclined surfaces, wherein the fourinclined surfaces meet at the single vertex, each of the four inclinedsurfaces is inclined with respect to a flat portion of the exit surface,and each of the inclined surfaces has a curved shape; four edges,wherein each of the four edges is disposed between the exit surface andthe single vertex and has a curved shape; and wherein the firstdiffusion member comprising the first and third edges has across-section in a first segment that is defined by an elliptical arc ofa first ellipse, which includes the first and third edges, and a chordconnecting both ends of the elliptical arc of the first ellipse, and thefirst diffusion member comprising the second and fourth edges has across-section in a second segment that is defined by an elliptical arcof a second ellipse, which includes the second and fourth edges, and achord connecting both ends of the elliptical arc of the second ellipse.2. The backlight assembly of claim 1, wherein each of the four inclinedsurfaces has a curved shape in horizontal sectional view.
 3. Thebacklight assembly of claim 1, wherein two edges have a curved shape invertical sectional view taken along the two edges of the four edges, andeach of the four inclined surfaces has a curved shape in verticalsectional view.
 4. The backlight assembly of claim 1, wherein the firstdiffusion member has a bottom surface that is in contact with the exitsurface, and side of the bottom surface meets lower end of each of thefour inclined surfaces.
 5. The backlight assembly of claim 4, whereinthe four edges comprise a first edge, a second edge, a third edge, and afourth edge, and the four inclined surfaces comprise: a first inclinedsurface comprising the first and second edges; a second inclined surfacecomprising the third edge and co-owning the second edge with the firstsurface; a third inclined surface comprising the fourth edge andco-owning the third edge with the second surface; and a fourth inclinedsurface co-owning the first edge with the first surface and co-owningthe fourth edge with the third surface, and the first to fourth edgeshave the curved shape.
 6. The backlight assembly of claim 1, wherein aratio of a minor axis of the first ellipse to a major axis of theellipse is 1:1 to 1:3, and a ratio of a minor axis of the second ellipseto a major axis of the ellipse is 1:1 to 1:3.
 7. The backlight assemblyof claim 1, wherein the first segment has a same shape as the secondsegment.
 8. The backlight assembly of claim 1, wherein the chord of eachof the first and second segments has a length of about 30 micrometers toabout 100 micrometers, a straight distance between the vertex and thechord of the first segment is equal to or smaller than about 15micrometers to about 50 micrometers, and a straight distance between thevertex and the chord of the second segment is equal to or smaller thanabout 15 micrometers to about 50 micrometers.
 9. The backlight assemblyof claim 1, wherein the light source comprises a plurality of pointlight sources spaced apart from each other.
 10. The backlight assemblyclaim 9, wherein each of the point light sources is a light emittingdiode.
 11. The backlight assembly of claim 9, wherein two point lightsources adjacent to each other and arranged in a first direction arespaced apart from each other by a distance of about 25 millimeters, andtwo point light sources adjacent to each other and arranged in a seconddirection substantially perpendicular to the first direction are spacedapart from each other by a distance of about 28 millimeters, and adistance between the first optical member and each of the point lightsources is equal to or smaller than 10 millimeters.
 12. The backlightassembly of claim 1, further comprising a second diffusion member thathas a shape that protrudes from the incident surface to diffuse thelight.
 13. The backlight assembly of claim 12, wherein the incidentsurface comprises a first area corresponding to an area on the incidentsurface covered by each point light source and a second areacorresponding an area on the incident surface between two point lightsources adjacent to each other, and the second diffusion members arespaced farther apart in the second area than in the first area, and aspace between each second diffusion member is greatest in a center ofthe second area and decreases toward the first area.
 14. The backlightassembly of claim 1, further comprising a second optical member facingthe light source while interposing the first optical member between thelight source and the second optical member, wherein the second opticalmember comprises: a reflective polarizer that reflects or transmits thelight from the light source according to a vibration direction of thelight; a prism sheet that condenses the light from the reflectivepolarizer; and a diffusion sheet that diffuses the light providedthrough the prism sheet.
 15. The backlight assembly of claim 1, whereineach of the four inclined surfaces has a predetermined curvature.
 16. Adisplay apparatus comprising: a backlight assembly comprising a lightsource that generates a light and a first optical member that diffusesthe light; and a display panel receiving the light from the backlightassembly to display an image, wherein the first optical membercomprises: a body including an incident surface to which the tiara isincident and an exit surface facing the incident surface, from which thelight exits; and a first diffusion member disposed on the exit surfaceto diffuse the light, wherein the first diffusion member comprises: asingle vertex; four inclined surfaces, wherein the four inclinedsurfaces meet at the single vertex, each of the four inclined surfacesis inclined with respect to a flat portion of the exit surface, and eachof the inclined surfaces has a curved shape; four edges, wherein each ofthe four edges is disposed between the exit surface and the singlevertex and has a curved shape; and a second diffusion member that has ashape that protrudes from the incident surface to diffuse the light,wherein the incident surface comprises a first area corresponding to anarea on the incident surface covered by each point light source and asecond area corresponding to an area on the incident surface between twopoint light sources adjacent to each other, and the second diffusionmembers are spaced farther apart in the second area than in the firstarea and a space between each second diffusion member is greatest in acenter of the second area and decreases toward the first area.
 17. Thedisplay apparatus of claim 16, wherein each of the four inclinedsurfaces has a curved shape in horizontal sectional view.
 18. Thedisplay apparatus of claim 16, wherein two edges have a curved shape invertical sectional view taken along the two edges of the four edges, andeach of the four inclined surfaces has a curved shape in verticalsectional view.
 19. The display apparatus of claim 16, wherein the firstdiffusion member has a bottom surface that is in contact with the exitsurface, and side of the bottom surface meets lower end of each of thefour inclined surfaces.
 20. The display apparatus of claim 19, whereinthe four edges comprise a first edge, a second edge, a third edge, and afourth edge, and the inclined surfaces comprise: a first inclinedsurface comprising the first and second edges; a second inclined surfacecomprising the third edge and co-owning the second edge with the firstsurface; a third inclined surface comprising the fourth edge andco-owning the third edge with the second surface; and a fourth inclinedsurface co-owning the first edge with the first surface and co-owningthe fourth edge with the third surface, and the first to fourth edgeshave the curved shape.
 21. The display apparatus of claim 20, whereinthe first diffusion member comprising the first and third edges has across-section in a first segment that is defined by an elliptical arc ofa first ellipse, which includes the first and third edges, and a chordconnecting both ends of the elliptical arc of the first ellipse, thefirst diffusion member comprising the second and fourth edges has across-section in a second segment that is defined by an elliptical arcof a second ellipse, which includes the second and fourth edges, and achord connecting both ends of the elliptical arc of the second ellipse,a ratio of a minor axis of the first ellipse to a major axis of theellipse is 1:1 to 1:3, and a ratio of a minor axis of the second ellipseto a major axis of the ellipse is 1:1 to 1:3.
 22. The display apparatusof claim 21, wherein the light source comprises a plurality of pointlight sources spaced apart from each other.